The present invention relates to a numerical control system for controlling various machines such as wire-cut electrospark machine, turret punch press, composite machine tool and so forth and, more particularly, to a numerical control system in which various functions are coupled by means of optical fibers.
Most current numerical control systems (referred to as "NC system", hereinafter) incorporate computers. More specifically, these NC systems have the following constituent elements: a processing device such as a microprocessor adapted to perform various processings such as numerical control processing, edit processing, transmission and receiving of data and so forth, in accordance with a control program and a machining program; memories such as a nonvolatile data memory, a working memory and a control program memory; a paper tape reader and a paper tape puncher; a control panel incorporating a display device; an external storage medium such as cassette type magnetic tape; and a heavy current circuit for signal exchange between the controller and the machine, e.g. delivery of signals, such as a miscellaneous function command or a spindle rotation command, to the machine and delivery of work completion signals to the controller upon confirming the completion of the work in response to the miscellaneous function command or the spindle rotation command. The NC system further includes servomotor units having driving motors for positioning the spindle in the directions of X,Y and Z axes, and a pulse distributor for distributing pulses to these servo units.
In these known NC systems, the exchange of data between different functional blocks (for example, paper tape reader and microprocessor) in the system is made through a data bus, while the delivery of the address is made through an address bus. As a matter of fact, in order to concurrently send signals comprising n bits constituting each unit of data, each data bus includes n lines, so that the connection of bus lines between associated functional blocks is very complicated. In addition, since the NC systems are usually used in factories or the like where there is a lot of electrical noise, the address bus often and the data bus tend to pick up the electrical noise resulting in a malfunction of the NC system. Another problem of the prior art is that a specific consideration or measure is required to standarize the interface between associated functional blocks which raises the cost of the NC system.